Seasonal And Spatial Variability Of Surface Ozone Over China

Both limited observations and3-D chemical tranport model suggest that surfaceozone over China features a summertime trough differring by latitude and season,which does not share the same pattern in US and Europe with the same latitude. Wethen investigate the seasonal and spatial distributions of surface ozone over Chinawith the GEOS-Chem global transport model and TES satellite data. Firstly, weevaluate the model results with the surface observation and TES satellite data; Thenwe quantify the the contributions of background ozone, Chinese anthropogenicpollutions and external sources on this variability with the anthropogenic pollutesclose in these regions individually; Besides we conduct tagged ozone offlinesimulation to analyze the seansonal variations and transport of the foreign sources,such as Europe and North America; We furth take a look at how the natural sourcesinfluence the surface ozone. In the end, we briefly discuss the interannual variationsof surface ozone over China influenced by the2006EI Ni o with consecutive threeyears of observation by TES satellite.Annual mean background ozone over China shows a spatial gradient from55ppbv in northwest to20ppbv in southeast region, corresponding with changes intopography and ozone life time. The natural background ozone dominates over50%of the total ozone in most regions, especialy in west. Annual mean pollutionbackground ozone is12.6ppbv and shows a minimum in summer and a maximum inspring. This is due to the seasonal variations of regional transport and ozone lifetime.China pollution ozone peaks in summer in June north of Yangtze River or autumn inOctober south of it and reach its minimum in winter time. Its greatest value variesbetween20-25ppbv in these two regioins. Tagged ozone simulation suggests that thelong-range transport of ozone from northen mid-latitude continents (including Europeand North America) also reaches a minimum in the summer, whereas ozone fromSoutheast Asia exhibits a maximum over eastern China in summer, which value iseven greater than the Europe and North Amerca influences. Accoring to the study, it shows that the seasonal switch of monsoonal wind patterns plays a significant role indetermining the seasonality of background ozone over China.The ozone and carbon monoxide from August to December in the year2006aregreatly higher than that in the same months of2005and2007, which is influenced bythe significant2006EI Ni o phenomenon. The remarbly region is centered on thesouth of30oN. The discrepancies for ozone over these three years peaks in Oct, whilein November for carbon monoxide.